On the understanding and analyses of dust deposition on Heliostat

In Rajasthan, the received solar irradiation is high, however, dry and dusty atmosphere are issues for harnessing of solar energy. The high speed wind characteristic of Rajasthan can initiate the saltation process, which in turn removes and carries dust from ground and deposit on collecting surfaces, such as, heliostats. This in turn reduces the collection and therefore the overall efficiency of concentrating solar thermal system. Dust deposition on flat mirror plates depends on various factors like heliostat field density, soil composition, atmospheric condition, mirror orientation, wind speed, plate material, height and structure of heliostat etc. In this article, experiments on dust deposition by wind onto a mirror simulating a heliostat model in wind tunnel are presented. Further, the performed analyses of dust deposition on single and multiple heliostats are described. These clearly indicate the influence of flow and position of heliostat. Furthermore, the obtained observations indicate a possible way of mitigating cleaning effort with localized deposition.